Hydrogen peroxide is a strong oxidizing agent. It is unclear what impact it may have on collagen fibers during degradation and any subsequent effects on the rate of conversion from collagen fibers to gelatin. Thus, we investigated the relationship between internal structures and macroscopic properties during collagen degradation. Specifically, we analyzed the change in mechanical properties and the structure of tilapia skin collagen fibers during thermal extraction in the presence of hydrogen peroxide. Our goals were to understand the process behind hydrogen peroxide-induced collagen fiber degradation. Such insight can help better control the degradation reaction, as well as provide a new strategy for producing high gel strength gelatin and improved gelatin production efficiency.